...[Germany] had tough gun laws; they had a school shooting. They tightened those tough gun laws; they had another school shooting.

To state the obvious: A man intent on mass murder is not deterred by misdemeanor level possession/purchase laws. He's bound for prison or death by cop; he is not sweating the lesser laws he may break en route to a massive slaughter of children.

...Strict gun laws, loose gun laws: An intensely motivated lunatic is going to find a way to make his fantasy real. --Ace.